A U.S. nuclear-powered aircraft carrier arrived at a port in the South Korean city of Busan on Tuesday, as tensions ratchet up with North Korea following a series of missile tests and other provocations.

The warship's arrival came a day after North Korea fired two ballistic missiles in an apparent response to U.S.-South Korea joint military exercises and, according to the North's state media, leader Kim Jong Un inspected work related to the country's nuclear weapons program.

The USS Nimitz, a U.S. Navy aircraft carrier, makes a port call in Busan, South Korea, on March 28, 2023. (Kyodo) ==Kyodo

It is the first time since September last year that a U.S. nuclear carrier entered a South Korean port.

The U.S. Navy's Nimitz docked after its strike group participated in a training exercise with the South Korean navy in open waters near South Korea's southern island of Jeju on Monday.

A welcome ceremony is held in Busan as a U.S. nuclear-powered aircraft carrier, the USS Nimitz, arrives at the South Korean port city on March 28, 2023. (Kyodo) ==Kyodo

It also conducted a drill with the Japanese Maritime Self-Defense Force in the Pacific Ocean and the East China Sea for four days through Sunday.

Rear Adm. Christopher Sweeney, commander of Carrier Strike Group 11, told a news conference on the aircraft carrier that the United States, South Korea and Japan plan to conduct a joint exercise after leaving Busan.

The carrier's arrival in South Korea will strengthen friendly cooperation as well as joint readiness posture in commemoration of the 70th anniversary of the alliance, South Korea's Defense Ministry said.

Freedom Shield, the two countries' regular springtime exercise, ended Thursday after 11 days in which the nations' navies held large-scale drills. It was the first time in five years the exercise had been held.

An amphibious landing exercise is under way and runs through next Monday.

The USS Nimitz, a U.S. Navy aircraft carrier, makes a port call in Busan, South Korea, on March 28, 2023. (Kyodo) ==Kyodo

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